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THE HARMFUL ACTION OF DISTILLED WATER 263 
In order to bring out the relative rate of extraction more clearly, 
the following table is compiled from the foregoing data. It shows the 
rate of leaching as gain in conductivity expressed in units per root per 
day of 24 hours. 
Table VII 
Rates for Leaching per Root per Day 
Time of 
experiment Four roots o ts 
24 hours 0.151 X 10-4 0.155 X 10-4 
48 hours 0.135 X 10-4 0.177 X 10-4 
72 hours 0.1 10 X 10-4 0.134 X 10-4 
This comparison shows that in the experiment with 4 roots the 
leaching continues through the longest period tested, 72 hours, but at 
a clearly decreasing rate. The regularity seen here is not found in the 
experiment with 10 roots. It is interesting to note in this connection 
that the conductivity of the check decreases during the longer periods, 
a point to which attention will be recalled later. It is important in 
this connection to note that the growth rate of the culture containing 
4 roots falls off in a manner suggesting a parallel with the decrease in 
resistance. As the distilled water progressively extracts electrolytes, 
and perhaps other substances, from the plant the growth rate di- 
minishes and almost ceases. In view of the fact demonstrated in 
earlier studies that the primary radicle of the white lupine seems to be 
unable to recover in distilled water, seedlings were not exposed for a 
longer period. 
The results seen above seem to indicate that the leaching process 
begins actively when the roots enter the solution, and during the 72- 
hour period in which the roots remain there continues at a somewhat 
decreasing rate. It was thought desirable to follow 'somewhat further 
the course of the changes in conductivity and to try to ascertain 
whether with the accumulation of the leached materials the extraction 
of the plants continued. Accordingly cultures were arranged in 
which six series of plants were used: (i) In 150 c.c. of distilled water, 
4 plants; (2) in the same volume, 10 plants; (3) in the like volume, no 
plants; (4) in the Hke volume of Potomac water, 4 plants; (5) in the 
same volume of Potomac water, 10 plants, and (6) in the same volume 
of Potomac water, no plants. Since it was desired to test the physio- 
logical properties of these media as affected by the gain of solutes 
from the leached roots or by the loss of dissolved material through 
